<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .wrap{
            display: flex;
        }
        .one{
            /* 设置弹性盒子内部子元素在盒子主轴上所占的空间 */
            flex: 1;
        }
        .two{
            flex: 2;
            height: 100px;
            background-color: greenyellow;
        }
        .three{
            flex: 3;
        }
        .box{
            width: 200px;
            height: 100px;
            background-color: pink;
        }
    </style>
</head>
<body>
    <div class="wrap">
        <div class="box one">one</div>
        <div class="two">two</div>
        <div class="box three">three</div>
    </div>
</body>
</html>